Various clinical procedures exist for introducing medical devices, such as stents, valves, filters, and other intraluminal medical devices, into a body vessel. For example, a percutaneous introduction technique typically includes the insertion of a hollow needle through the skin and into a desired blood vessel, which creates a puncture site. A guidewire is then advanced through the needle and into the blood vessel via the puncture site. The needle is subsequently withdrawn, leaving the guidewire partially disposed within the blood vessel and partially disposed outside the body. A dilator is then advanced over the guidewire into the blood vessel such that gradual, proximally-directed insertion of the dilator progressively enlarges the diameter of the puncture site until it is suitable for advancement of a sheath having a lumen into the blood vessel. The sheath is then advanced over the guidewire and into the blood vessel. Next, the dilator is removed to leave the sheath and guidewire in place, which can then be used for insertion of a catheter or other medical device into the blood vessel via the lumen of the sheath.
Removal of the dilator can add time and complexity to a procedure where the loss of established access is a concern. In addition, the act of removing a dilator can change the position of the distal end of the sheath disposed within the body vessel and/or can change the position of the distal end of the guidewire, which can create inaccuracy in the position of a treatment being delivered and/or performed, and may necessitate additional navigation of the sheath and/or guidewire in an attempt to eliminate or reduce such inaccuracy. For example, if the position of the distal end of the guidewire has been altered during removal of the dilator, additional imaging may be required to confirm or adjust the guidewire's placement. A need exists, therefore, for improved devices and methods useful in the introduction of medical devices into body vessels.